1. Field of the Invention
This invention relates to an improved treatment of diseased or occluded vascular grafts in patients having undergone coronary artery bypass surgery.
2. Description of the Related Art
Coronary artery disease is a major problem in the U.S. and throughout the world. Coronary arteries as well as other blood vessels frequently become clogged with plaque, which at the very least impairs the efficiency of the heart's pumping action, and can lead to heart attack and death. In some cases, these arteries can be unblocked through non-invasive techniques such as balloon angioplasty. In more difficult cases, a bypass of the blocked vessel is necessary.
In a bypass operation, one or more venous segments are inserted between the aorta and the coronary artery. The inserted venous segments or transplants act as a bypass of the blocked portion of the coronary artery and thus provide for a free or unobstructed flow of blood to the heart. More than 500,000 bypass procedures are performed in the U.S. every year.
Such coronary artery bypass surgery, however, is a very intrusive procedure that is expensive, time-consuming and traumatic to the patient. The operation requires an incision through the patient's sternum (sternotomy), and that the patient be placed on a bypass pump so that the heart can be operated on while not beating. A saphenous vein graft is harvested from the patient's leg, another highly invasive procedure, and a delicate surgical procedure is required to piece the bypass graft to the coronary artery (anastomosis). Hospital stays subsequent to the surgery and convalescence are prolonged.
Over time, the vein graft itself may become diseased, stenosed, or occluded, similar to the original bypassed vessel. Old, diffusely diseased saphenous vein grafts are considered contraindications for angioplasty and atherectomy, severely limiting the options for minimally invasive treatment. Some diseased or occluded saphenous vein grafts are associated with acute ischemic syndromes, however, necessitating some form of intervention.
Thus, there is a need for an improved treatment of diseased or occluded grafts in patients having had coronary bypass surgery.